A method and apparatus for controlling read-out and/or synchronization between an external magnetic field and written data during a reading operation from a magneto-optical recording medium includes generating a pulse in a reading signal in a read-out layer by copying a mark region from a storage layer to the read-out layer upon heating by a radiation power and with the aid of the external magnetic field. The waveform of the reading signal is analyzed, and the analysis result is used for correcting a phase deviation and/or for controlling a copy window size of the mark copying. Phase errors may thus be corrected for any size of the copy window. Even small changes in the copy window can be detected and corrected.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of controlling read-out from a magneto-optical recording medium, said recording medium comprising a storage layer and a read-out layer, wherein an expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by a radiation power and with the aid of an external magnetic field, said method comprising the acts of: providing said reading signal to a clock generator for generation of a clock signal supplied to an optical pick-up unit and a magnetic head driver; an analysis act including providing said reading signal to an analyzer for analyzing the waveform of said reading signal and forming an analysis signal, and a controlling act including providing said analysis signal to a controller for controlling a copy window size of said mark copying based on said analysis signal by applying a first control signal to said optical pick-up unit and a second control signal to said magnetic head driver.
2. The method according to claim 1 , wherein said controlling step is performed by controlling said radiation power and/or the strength of said external magnetic field.
3. The method according to claim 1 , wherein synchronization phase errors between the external magnetic field, used for said mark copying, and written data are determined and used in said analyzing act.
4. A method according to claim 1 , wherein said reading signal is obtained by reading a test area provided on said recording medium.
5. The method according to claim 1 , wherein said reading signal is obtained by reading written user data.
6. The method according to claim 1 , wherein said analyzing act comprises comparison of a timing of a rising edge of a predetermined pulse of said reading signal with a reference value.
7. The method according to claim 1 , wherein said analyzing act comprises comparison of a duration of a predetermined pulse of said reading signal with a reference value.
8. The method according to claim 6 , wherein said predetermined pulse is a first pulse of a code run length.
9. The method according to claim 7 , wherein said duration is determined by detecting a pulse amplitude of said predetermined pulse after a filter operation.
10. The method according to claim 1 , wherein said analyzing act is performed by using information from a look-up table.
11. The method according to claim 10 , wherein said look-up table is updated based on information read from said recording medium.
12. The method according to claim 10 , wherein said information defines a relation between said waveform and at least one of a phase error and a copy window size.
13. The method according to claim 10 , wherein said look-up table is provided by a control program of a driver function used for generating said external magnetic field.
14. The method according to claim 1 , further comprising the acts of: storing on said recording medium strategy information defining a write strategy of said recording medium, and using said strategy information in said analyzing step.
15. The method according to claim 14 , wherein said strategy information is used for generating a reference waveform used in said analyzing step.
16. A reading apparatus for controlling read-out from a magneto-optical recording medium, said recording medium comprising a storage layer and a read-out layer, wherein an expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by a radiation power and with the aid of an external magnetic field, said apparatus comprising: a clock generator configured to receive said reading signal and generate a clock signal which is supplied to an optical pick-up unit and a magnetic head driver; analyzing means for analyzing the waveform of said reading signal and forming an analysis signal; and control means for controlling a copy window size of said mark copying based on said analysis signal by applying a first control signal to said optical pick-up unit and a second control signal to said magnetic head driver.
17. The reading apparatus according to claim 16 , wherein said analyzing means comprises storing means for storing information defining a relation between said waveform and at least one of a phase error and a copy window size.
18. The reading apparatus according to claim 17 , wherein said analyzing means comprises comparing means for comparing said analyzed waveform based on said relation stored in said storing means.
19. The reading apparatus according to claim 16 , wherein said reading apparatus is a disk player for MAMMOS disks.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 24, 2003
April 1, 2008
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